Connecting member of structure

ABSTRACT

A bracket includes a cylindrical portion and a plate-shaped portion that are integrally formed. The cylindrical portion is provided at one end side of a blank along one direction and is provided with a slit extending over an entire length of the cylindrical portion in the one direction as a result of forming a portion at the one end side of the blank along the one direction into a cylindrical shape extending in the one direction. The plate-shaped portion is provided at the other end side of the blank along the one direction. The cylindrical portion of the bracket is inserted in the cylindrical body member formed of an aluminum alloy material, and the body member and the cylindrical portion are clinched by electromagnetic tube compression.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a connecting member that connectsmembers to each other in a structure including a skeleton constructionof, for example, a building or an automobile.

2. Description of the Related Art

A structure including a skeleton construction of, for example, abuilding or an automobile is formed by assembling a plurality ofstrength members, such as side frames. Connecting members that connectmembers to each other for disposing the members apart from each otherwith a certain gap being provided therebetween in such a structure, orfor increasing the strength of such a structure are known (refer to, forexample, a reinforcement strut tower 21 in FIG. 2 in Japanese UnexaminedPatent Application Publication No. 2004-106704 (Patent Literature 1) andan inclined lower member 18 in FIGS. 2 and 3 in Japanese UnexaminedPatent Application Publication No. 2009-184424 (Patent Literature 2)).

In general, such connecting members described above are formed byassembling a plurality of members (formed by pressing a metallic plate)and by fastening the assembled members to each other using welding, or amechanical fastener such as a bolt. Here, when the members are weldedtogether, the members may become distorted due to welding heat.Therefore, in order to fasten the members together with good precisionwithout thermal distortion, a technology (such as that disclosed inJapanese Unexamined Patent Application Publication No. 2000-264246(Patent Literature 3)) of clinching the members to each other byelectromagnetic forming may be considered. That is, in Patent Literature3, one of two pipe sections is fitted to an interior of the other of thepipe sections, and a flux concentrating unit of an electromagneticforming device is placed in the vicinity of a portion where the two pipesections overlap each other, to generate a magnetic field. This causesan electromagnetic force generated by an induction current to act uponthe pipe sections, and the pipe sections to be compressed, as a resultof which the members are clinched to each other.

However, when two pipe sections, formed of nonmagnetic materials such asaluminum, are clinched to each other by electromagnetic forming,induction current is similarly generated at the inner member as well asat the outer member. Therefore, the outer member and the inner memberare both deformed in a diameter reduction direction. Consequently,sufficient clinching force is not obtained, as a result of sufficientstrength may not be provided in the connecting member that connects thestrength members of a structure to each other.

In recent years, there is an increasing demand for improvingdesignability, and other members are often disposed between connectionmembers that are to be connected by a connecting member. In such a case,it is necessary to form the connecting member with a shape that does notinterfere with the members that are disposed between the connectionmembers. As mentioned above, if the members that form a connectingmember are formed by a pressing operation, it may be difficult to formthe connecting member with a required shape.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide aconnecting member of a structure, which allows the structure to be morefreely designed, which is capable of being manufactured with goodprecision, and which provides high strength.

According to a first aspect of the present invention, there is provideda connecting member of a structure, including a cylindrical body memberand a bracket. The cylindrical body member is formed of a nonmagneticmaterial. The bracket includes a cylindrical portion and a plate-shapedportion that are integrally formed. The cylindrical portion is providedat one end side of a plate material along one direction and is providedwith a slit extending over an entire length of the cylindrical portionin the one direction as a result of forming a portion at the one endside of the plate material along the one direction into a cylindricalshape. The plate-shaped portion is provided at the other end side of theplate material along the one direction. At least one of two inner sidesat corresponding end portions of the body member has inserted thereinthe cylindrical portion of the bracket, and the cylindrical portion andthe body member are clinched by electromagnetic tube compression.

Since the connecting member of a structure is such that a bracket inwhich a cylindrical portion and a plate-shaped portion are integrallyformed is formed from a plate material, the cylindrical portion and theplate-shaped portion can be formed with various sizes and shapes.Therefore, the structure can be more freely designed. Since the bodymember and the bracket are clinched by electromagnetic tube compression,it is possible to fasten and secure both the body member and the bracketwith the bracket being fixed at a certain position. In addition, sincethermal distortion that occurs when the body member and the bracket arefastened by welding does not occur, it is possible to manufacture theconnecting member with good precision. Further, a slit extending overthe entire length of the cylindrical portion in one direction is formedin the cylindrical portion extending in the one direction. Therefore,when the cylindrical portion is inserted into the body member and thecylindrical portion and the body member are clinched by electromagnetictube compression, induction current is stopped at the slit in thecylindrical portion. Consequently, whereas the nonmagnetic body memberthat is disposed at the outer side of the cylindrical portion iscompressed, the cylindrical portion of the bracket that is positioned inthe body member is hardly compressed. Therefore, it is possible tofasten both the body member and the bracket with sufficient clinchingforce. This makes it possible to increase the strength of the connectingmember.

According to a second aspect of the present invention, there is provideda connecting member of a structure, including a cylindrical body memberand a bracket. The cylindrical body member is formed of a nonmagneticmaterial. The bracket includes a plate material and at least onereinforcing rib that is joined to a surface of the plate material. Atleast one of two inner sides at corresponding end portions of the bodymember has inserted therein a portion of the bracket to which the atleast one reinforcing rib is joined so that a direction of extension ofthe at least one reinforcing rib is along a direction of extension ofthe body member, and the body member and a portion of the bracketinserted in the body member are clinched by electromagnetic tubecompression.

Since the connecting member of a structure is such that the bracket isformed by joining a reinforcing rib to a plate material, the bracket canbe formed with various sizes and shapes. Therefore, the structure can bemore freely designed. Since the body member and the bracket are clinchedby electromagnetic tube compression, it is possible to fasten and secureboth the body member and the bracket with the bracket being fixed at acertain position. In addition, since thermal distortion that occurs whenthe body member and the bracket are fastened by welding does not occur,it is possible to manufacture the connecting member with good precision.Further, the reinforcing rib is joined to the portion of the bracketthat is inserted into the body member, so that this portion of thebracket has high rigidity. Therefore, when the bracket and the bodymember are clinched by electromagnetic tube compression, even ifinduction current is generated at the surface of the bracket, thebracket is hardly deformed, and only the nonmagnetic body member at theouter side of the reinforcing rib is compressed. Consequently, it ispossible to fasten both the body member and the bracket with sufficientclinching force. This makes it possible to increase the strength of theconnecting member. In addition, the body member that is compressed isnot deformed in the same shape as that before compression. Instead, thebody member is deformed in a cross-sectional shape having an unevenportion in accordance with the shape of the portion of the bracket towhich the reinforcing rib is joined. Therefore, it is possible toincrease the strength between the bracket and the body member in therotation direction (that is, withstand load in the rotation direction).Further, the reinforcing rib makes it is possible to considerablyincrease bending load of the bracket.

According to a third aspect of the present invention, there is provideda connecting member of a structure, including a cylindrical body memberand a bracket. The cylindrical body member is formed of a nonmagneticmaterial. The bracket includes a plate material and at least onereinforcing rib that is joined to a surface of the plate material. Theplate material is bent so that part of a portion of the plate materialto which the reinforcing rib is joined has a bend line extending in adirection that crosses a direction of extension of the at least onereinforcing rib. At least one of two inner sides at corresponding endportions of the body member has inserted therein a portion of thebracket to which the at least one reinforcing rib is joined so that thedirection of extension of the at least one reinforcing rib is along adirection of extension of the body member, and the body member and aportion of the bracket inserted in the body member are clinched byelectromagnetic tube compression.

Since the connecting member of a structure is such that the bracket isformed by joining a reinforcing rib to a plate material, the bracket canbe formed with various sizes and shapes. Therefore, the structure can bemore freely designed. Since the body member and the bracket are clinchedby electromagnetic tube compression, it is possible to fasten and secureboth the body member and the bracket with the bracket being fixed at acertain position. In addition, since thermal distortion that occurs whenthe body member and the bracket are fastened by welding does not occur,it is possible to manufacture the connecting member with good precision.Further, the reinforcing rib is joined to the portion of the bracketthat is inserted into the body member, so that this portion of thebracket has high rigidity. Therefore, when the bracket and the bodymember are clinched by electromagnetic tube compression, even ifinduction current is generated at the surface of the bracket, thebracket is hardly deformed, and only the nonmagnetic body member at theouter side of the reinforcing rib is compressed. Consequently, it ispossible to fasten both the body member and the bracket with sufficientclinching force. This makes it possible to increase the strength of theconnecting member. In addition, the body member that is compressed isnot deformed in the same shape as that before compression. Instead, thebody member is deformed in a cross-sectional shape having an unevenportion in accordance with the shape of the portion of the bracket towhich the reinforcing rib is joined. Therefore, it is possible toincrease the strength between the bracket and the body member in therotation direction (that is, withstand load in the rotation direction).The reinforcing rib makes it possible to considerably increase thebending load of the bracket. Further, it is possible to form a bentportion at the bracket. By this, even if there is an interference objectbetween connection members, it is possible to dispose the connectingmember away from the interference object. Therefore, the structure canbe even more freely designed.

In the connecting member of a structure according to any one of thefirst to third aspects, the body member may be bent.

In the connecting member of a structure, even if there exists aninterference object between connection members, it is possible todispose the connecting member away from the interference object as aresult of bending the body member. Therefore, the structure can be evenmore freely designed.

In the connecting member of a structure according to any one of thefirst to third aspects, at least part of the body member may beflattened.

In the connecting member of a structure, even if there exists aninterference object between connection members, it is possible todispose the connecting member away from the interference object as aresult of flattening the body member. Therefore, the structure can beeven more freely designed.

In the connecting member of a structure according to any one of thefirst to third aspects, it is possible to bend the body member, andflatten at least part of the body member.

In the connecting member of a structure, even if there exists aninterference object between connection members, it is possible todispose the connecting member away from the interference object as aresult of bending and flattening the body member. Therefore, thestructure can be even more freely designed.

It is possible to more freely design the structure, manufacture theconnecting member with good precision, and increase strength of theconnecting member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the structure of a front portion of the body ofan automobile to which a connecting member of a structure according tothe present invention is applied;

FIG. 2 is a front view of a connecting member according to a firstembodiment of the present invention;

FIG. 3 is a front view of a state of a bracket shown in FIG. 2 beforethe bracket is joined to a body member;

FIG. 4A is a perspective view of a blank before forming the bracketshown in FIG. 3;

FIG. 4B is a perspective view of a state after forming the bracket fromthe blank shown in FIG. 4A;

FIG. 5A illustrates steps of manufacturing the connecting member shownin FIG. 2 in the order in which the steps are performed, and a state inwhich cylindrical portions of brackets are being inserted intocorresponding ends of the body member;

FIG. 5B illustrates steps of manufacturing the connecting member shownin FIG. 2 in the order in which the steps are performed, and a state inwhich the cylindrical portions and the body member are being fastened toeach other;

FIG. 5C illustrates steps of manufacturing the connecting member shownin FIG. 2 in the order in which the steps are performed, and a completedconnecting member;

FIG. 6A is a perspective view of a blank according to a firstmodification of the first embodiment;

FIG. 6B is a sectional view taken along line VIB-VIB of the blank shownin FIG. 6A;

FIG. 6C is a perspective view of a bracket formed from the blank shownin FIG. 6A;

FIG. 7A is a perspective view of a blank according to a secondmodification of the first embodiment;

FIG. 7B is a sectional view taken along line VIIB-VIIB of the blankshown in FIG. 7A;

FIG. 7C is a perspective view of a bracket formed from the blank shownin FIG. 7A;

FIG. 8A illustrates a third modification of the first embodiment;

FIG. 8B is a top view of a connecting member shown in FIG. 8A;

FIG. 8C is a top view of a connecting member according to a fourthmodification of the first embodiment;

FIG. 9A is a perspective view of a blank according to a fifthmodification of the first embodiment;

FIG. 9B is a perspective view of a bracket formed from the blank shownin FIG. 9A;

FIG. 10 is a perspective view of a connecting member according to asecond embodiment of the present invention;

FIG. 11 is a side view of a bracket shown in FIG. 10;

FIG. 12 illustrates joining of a blank and a reinforcing rib shown inFIG. 10;

FIG. 13 is a sectional view taken along line XIII-XIII in FIG. 10;

FIG. 14A is a perspective view of a bracket according to a modificationof the second embodiment;

FIG. 14B is a side view of the bracket shown in FIG. 14A;

FIG. 15 illustrates a method for manufacturing a reinforcing rib shownin FIG. 14A.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are hereunder describedwith reference to the drawings.

In each embodiment, the case in which a connecting member 1 of astructure according to the present invention is applied to afront-portion structure 90 of the body of an automobile according to thepresent invention is described. In the description below, a proceedingdirection of the automobile corresponds to a “forward direction”, areceding direction of the automobile corresponds to a “backwarddirection”, and directions that are horizontal directions and that areorthogonal to the forward direction and the backward directioncorrespond to a “leftward direction” and a “rightward direction”.

As shown in FIG. 1, the front-portion structure 90 constituting anengine compartment that is positioned at the front portion of the bodyof the automobile includes left and right front side frames 91, a frontbumper beam 93, and upper side frames 94. The left and right front sideframes 91 are provided at the left and right sides of the front portionof the body, respectively. The front bumper beam 93 bridges front endportions of the left and right front side frames 91 (the front sideframe at the far side in FIG. 1 is not shown). The upper side frames 94are provided at outer sides of the left and right front side frames 91,respectively.

Each front side frame 91 extends in the front-back direction of thebody. A back end of each front side frame 91 is connected to a frontfloor frame 95 extending in the front-back direction of the body at alower side of an automobile cabin. Each upper side frame 94 extends inthe forward direction of the body from a front pillar 96 thatconstitutes a front end of a door opening portion of the automobilecabin. The connecting member 1 according to the embodiment connects thefront side frames 91 and the upper side frames 94 to each other.

First Embodiment

Next, the structure of a connecting member 1 according to a firstembodiment of the present invention is described with reference to FIG.2. The connecting member 1 includes a cylindrical body member 10 andbrackets 20 that are joined to corresponding ends of the body member 10.Compressed tube portions 11 are provided at two ends of the body member10. As described in detail below, the brackets 20 are clinched to thebody member 10 by electromagnetic tube compression. In the firstembodiment, the body member 10 is formed of aluminum alloy, and eachbracket 20 is formed of soft steel. That is, the body member 10 is anonmagnetic member, and each bracket 20 is a magnetic member. Eachbracket 20 has bolt holes 24 for receiving bolts for mounting theconnecting member 1 to connection members (the front side frames 91 andthe upper side frames 94 in the embodiment). In the embodiment, eachbracket 20 has four bolt holes 24.

Here, each bracket 20 is described in detail with reference to FIGS. 3and 4A and 4B. Each bracket 20 includes a cylindrical portion 21 and aplate-shaped portion 22. Each cylindrical portion 21 is a portion thatis inserted into the cylindrical body member 10. One end of eachcylindrical portion 21 is formed consecutively with its correspondingplate-shaped portion 22. Each plate-shaped portion 22 is a portion thatis mounted to a connection member, and is provided with theaforementioned bolt holes 24.

Each bracket 20 is formed by bending a plate-shaped blank 1020. Eachcylindrical portion 21 is integrally formed with its correspondingplate-shaped portion 22. As shown in FIG. 4A, the blank 1020 includes anarrow width portion 1021 (lower right portion), which is positioned atone end side along one direction (from the lower right to upper left inthe plane of FIGS. 4A and 4B), and a wide width portion 1022 (upper leftportion), which is positioned at the other end side along the onedirection and which has a width that corresponds to a length that isgreater than the width of the narrow width portion 1021, the lengthbeing defined in a direction orthogonal to the one direction. The narrowwidth portion 1021 is a portion that becomes the cylindrical portion 21when the bracket 20 is completed. The wide width portion 1022 is aportion that becomes the plate-shaped portion 22 when the bracket 20 iscompleted, and has holes 1024 that become the bolt holes 24 of theplate-shaped portion 22. In the embodiment, the blank 1020 is a platematerial having a uniform thickness.

By, for example, pressing a rod-shaped jig extending in the onedirection against a width-direction central portion of the blank 1020shown in FIG. 4A, the narrow width portion 1021 is subjected to bendingfor forming the narrow width portion 1021 into a cylindrical shapeextending in the one direction. As a result, the bracket 20 shown inFIG. 4B is formed. The two ends of the narrow width portion 1021 in thewidth direction are separated from each other by a slight gap when thenarrow width portion 1021 is formed into the cylindrical shape. That is,the slit 23 that extends in the one direction is formed over the entirelength of the cylindrical portion of the bracket 20.

Next, the procedure for manufacturing the connecting member 1 byclinching each bracket 20 to the body member 10 by electromagnetic tubecompression is described with reference to FIGS. 5A, 5B, and 5C. First,as shown in FIG. 5A, the cylindrical portions 21 of the correspondingbrackets 20 are inserted into corresponding ends of the body member 10.

As shown in FIG. 5B, an electromagnetic forming unit 7 is disposed at anouter side of a portion where the cylindrical portion 21 and the bodymember 10 overlap each other. The electromagnetic forming unit 7includes a coil 7 a, which is connected to a power supply (not shown),and a magnetic flux concentrating unit 7 b, which is provided at aninner side of the coil 7 a and which concentrates magnetic flux that isgenerated from the coil 7 a. That is, the magnetic flux concentratingunit 7 b opposes an outer peripheral surface of the portion of the bodymember 10 that overlaps the cylindrical portion 21.

When an instantaneous high current flows through the coil 7 a from thepower supply, magnetic flux generated from the coil 7 a concentrates ata surface of the magnetic flux concentrating unit 7 b that opposes theouter peripheral surface of the portion of the body member 10 thatoverlaps the cylindrical portion 21. At this time, induction current isgenerated at the nonmagnetic body member 10. By interaction between theinduction current and an electromagnetic field, a force that tries towiden an interval between the magnetic flux concentrating unit 7 b andthe outer peripheral surface of the portion of the body member 10 thatoverlaps the cylindrical portion 21, that is, a force that causes thebody member 10 to be compressed at the portion where the body member 10and the cylindrical portion 21 overlap each other (electromagneticforce) acts upon the body member 10.

In contrast, since the bracket 20 is a magnetic member, almost noinduction current is generated at the cylindrical portion 21. Inaddition, at the cylindrical portion 21, the induction current isinterrupted by the slit 23. Therefore, almost no force capable ofcompressing the cylindrical portion 21 acts upon the cylindrical portion21. That is, whereas the body member 10 that is disposed at the outerside of the cylindrical portion 21 is compressed, the cylindricalportion 21 of the bracket 20 that is positioned in the body member 10 ishardly compressed. Therefore, the portion where the body member 10 andthe cylindrical portion 21 overlap each other is clinched by theelectromagnetic tube compression of the body member 10. At this time,the cylindrical portion 21 of the bracket 20 acts as an inner mold, andis properly clinched with the body member 10 subjected to tubecompression forming from the outer side.

As shown in FIG. 5B, electromagnetic forming is performed in a state inwhich the plate-shaped portions 22 of the brackets 20 inserted in thecorresponding ends of the body member 10 are contacted withcorresponding jigs 8 and the brackets 20 are secured at certainpositions.

As mentioned above, the connecting member 1 shown in FIG. 5C iscompleted by clinching the body member 10 and the cylindrical portions21 of the brackets 20, inserted in the corresponding ends of the bodymember 10, by electromagnetic tube compression.

As mentioned above, according to the connecting member 1 of theembodiment, in each bracket 20, the cylindrical portion 21 and theplate-shaped portion 22 are integrally formed. As a result of forming aportion at one end side of the plate-shaped blank 1020 along the onedirection into a cylindrical shape extending in the one direction, thecylindrical portion 21 is provided at the one end side of the blank 1020along the one direction, and is provided with the slit 23 extending overits entire length in the one direction. The plate-shaped portion 22 isprovided at the other end side of the blank 1020 along the onedirection. The cylindrical portion 21 of each bracket 20 is inserted inthe cylindrical body member 10, formed of an aluminum alloy material,and the body member 10 and the cylindrical portions 21 are clinched byelectromagnetic tube compression.

Therefore, since the brackets 20 in which the cylindrical portions 21and the plate-shaped portions 22 are integrally formed are formed fromthe blanks 1020, it is possible to form the cylindrical portions 21 andthe plate-shaped portions 22 with various sizes and shapes. Thus, astructure to which the connecting member 1 is applied can be more freelydesigned. Since the body member 10 and the brackets 20 are clinched byelectromagnetic tube compression, it is possible to fasten and securethe body member 10 and the brackets 20 with the brackets 20 being fixedat certain positions. In addition, since thermal distortion that occurswhen the body member 10 and the brackets 20 are fastened by welding doesnot occur, it is possible to manufacture the connecting member 1 withgood precision. Further, the slit 23 extending over the entire length ofits corresponding cylindrical portion 21 in the one direction is formedin its corresponding cylindrical portion extending in the one direction.Therefore, when each cylindrical portion 21 is inserted into the bodymember 10 and each cylindrical portion 21 and the body member 10 areclinched by electromagnetic tube compression, induction current isstopped at the slit 23 in its corresponding cylindrical portion 21.Consequently, whereas the nonmagnetic body member 10 that is disposed atthe outer side of the cylindrical portions 21 is compressed, thecylindrical portions 21 of the brackets 20 that are positioned in thebody member 10 are hardly compressed. Therefore, it is possible tofasten the body member 10 and the brackets 20 with sufficient clinchingforce. This makes it possible to increase the strength of the connectingmember 1.

In the connecting member 1 according to the embodiment, each bracket 20is a magnetic member formed of soft steel. Therefore, when thecylindrical portions 21 of the brackets 20 and the body member 10 areclinched by electromagnetic tube compression, the cylindrical portions21 are hardly compressed even if induction current is generated. Thus,it is possible to increase clinching force for fastening the cylindricalportions 21 and the body member 10 to each other.

Further, in the connecting member 1 according to the embodiment, thecylindrical portions 21 of the brackets 22 and the body member 10 arefastened to each other by disposing the cylindrical portions 21 of thebrackets 20 in the body member 10 (formed of a nonmagnetic material),causing electric current to flow through the coil 7 a disposed at theouter side of the body member 10, and compressing the body member 10.Therefore, the size of the portions where the body member 10 arefastened to the brackets 20 is not large. That is, if the cylindricalportions 21 of the brackets 20 are to be disposed at the outer side ofthe body member 10 (formed of a nonmagnetic material), it is necessaryto expand the body member 10 by electromagnetic forming and to disposethe coil in the body member 10. If the diameter of the coil for anelectromagnetic forming operation is small, a sufficient expanding forcecannot be obtained. Therefore, the coil cannot be reduced in size. Thus,the portions where the body member 10 and the brackets members 20 arefastened to each other become large.

Modifications of First Embodiment

Next, a first modification and a second modification of theabove-described first embodiment are described with reference to FIGS.6A to 6C and FIGS. 7A to 7C. A connecting member according to the firstmodification and a connecting member according to the secondmodification differ from the connecting member according to the firstembodiment only in the shapes of brackets 120 and brackets 220corresponding to the brackets 20 according to the first embodiment. Theother structural features are substantially the same as those of thefirst embodiment. Therefore, they are given reference numerals that arethe same as those of their corresponding structural features accordingto the first embodiment, and are not described below.

As shown in FIGS. 6A and 6B, a recessed groove 1125 extending in a widthdirection of a narrow width portion 1121 and formed over the entirewidth of the narrow width portion 1121 is formed in a blank 1120 fromwhich a bracket 120 according to the first modification is formed. Bybending such a blank 1120 and integrally forming a cylindrical portion121 and a plate-shaped portion 122 to each other, the bracket 120 shownin FIG. 6C is completed. At the time of completion, by the recessedgroove 1125 formed in the blank 1120, a bead 125, which is a recessedportion extending inwardly in the cylindrical portion 121 is formed overthe entire periphery of the cylindrical portion 121 in a peripheraldirection thereof.

As shown in FIGS. 7A and 7B, a plurality of recessed portions 1225 (fourrecessed portions 1225 in the second modification), which are circularin plan view, are formed in the narrow width portion 1121 of a blank1220 from which a bracket 220 according to the second modification isformed. By bending such a blank 1220 and integrally forming thecylindrical portion 221 and the plate-shaped portion 222, the bracket220 shown in FIG. 7C is completed. At this time, the recessed portions1225 in the blank 1220 become dimples 225, which are recessed portionsextending inwardly in the cylindrical portion 221.

In the bracket 120 according to the first modification, the recessedgroove 1125, which becomes the bead 125, can be provided by pressforming or rolling forming, and can be formed at the same time thatholes 1124, which become bolt holes 124, are formed. Similarly, in thebracket 220 according to the second modification, the recessed portions1225, which become the dimples 225, can be provided by press forming orrolling forming, and can be formed at the same time that holes 1224,which become bolt holes 224, are formed.

According to the first modification, when the cylindrical portion 121and the body member 10 are clinched by electromagnetic tube compression,the body member 10 that is disposed at the outer side of the cylindricalportion 121 and that is compressed enters the bead 125 of thecylindrical portion 121 disposed in the body member 10. Similarly,according to the second modification, when the cylindrical portion 221and the body member 10 are clinched by electromagnetic tube compression,the body member 10 that is disposed at the outer side of the cylindricalportion 221 and that is compressed enters the dimples 225 of thecylindrical portion 221 disposed in the body member 10. Therefore, it ispossible to prevent the cylindrical portions 121 and 221 and the bodymember 10 from being shifted from each other after they have beenfastened to each other. That is, in the first modification, the bead 125that is formed over the entire periphery of the cylindrical portion 121in the peripheral direction makes it possible to prevent the cylindricalportion 121 from being removed from the body member 10. In the secondmodification, the dimples 225 make it possible to prevent thecylindrical portion 221 from being removed from the body member 10 andfrom rotating in the body member 10.

Next, a third modification and a fourth modification of theabove-described first embodiment are described with reference to FIGS.8A, 8B, and 8C. A connecting member according to the third modificationand a connecting member according to the fourth modification differ fromthe connecting member according to the first embodiment only in theshape of a body member 310 and a body member 410 corresponding to thebody member 10 according to the first embodiment. The other structuralfeatures are substantially the same as those of the first embodiment.Therefore, they are given reference numerals that are the same as thoseof their corresponding structural features according to the firstembodiment, and are not described below.

As shown in FIGS. 8A and 8B, the body member 310 according to the thirdmodification is bent. That is, the body member 310 is a cylindricalmember having a bent portion 312 at a substantially central portionthereof. By bending the body member 310 in this way, as shown in FIG.8A, even if there exists an interference object 4 between connectionmembers 2 and 3 that are connected to each other by the connectingmember 301, the connecting member 301 can be disposed. Although, in thethird modification, only one bent portion 312 is provided, a pluralityof bent portions 312 may be provided in accordance with the size andshape of the interference object 4.

As shown in FIG. 8C, the body member 410 according to the fourthmodification is flattened at a central portion thereof. That is, thebody member 410 is a cylindrical member having a flattened portion 412at the central portion thereof. By flattening the body member 410 inthis way, as in the third modification, the body member 410 can bedisposed away from the interference object 4 disposed between theconnection members 2 and 3. The size and position of the flattenedportion 412 can be set as appropriate in accordance with the size andshape of the interference object 4. For example, the entire body member410 may be flattened.

Further, a fifth modification of the above-described first embodiment isdescribed with reference to FIGS. 9A and 9B. A connecting memberaccording to the fifth modification differs from the connecting memberaccording to the first embodiment only in the shape of a bracket 520corresponding to the bracket 20 according to the first embodiment. Theother structural features are substantially the same as those of thefirst embodiment. Therefore, they are given reference numerals that arethe same as those of their corresponding structural features accordingto the first embodiment, and are not described below.

As shown in FIGS. 9A and 9B, a blank 1520 from which the bracket 520according to the fifth modification is formed is what is called atailored blank. The plate thickness of a narrow width portion 1521 isless than the plate thickness of a wide width portion 1522. That is, inthe bracket 520 that is formed from the above-described blank 1520, theplate thickness of a cylindrical portion 521 is less than the platethickness of a plate-shaped portion 522. By setting the plate thicknessof the cylindrical portion 521 and the plate thickness of theplate-shaped portion 522 to different plate thicknesses, it is possibleto change the strength in accordance with various structures. Although,in the fifth modification, the case in which the plate thickness of thecylindrical portion 521 is less than the plate thickness of theplate-shaped portion 522 is described, the plate thickness of thecylindrical portion 521 may be greater than the plate thickness of theplate-shaped portion 522.

Second Embodiment

Next, the structure of a connecting member 601 according to a secondembodiment of the present invention is described. The connecting member601 according to the second embodiment differs from the connectingmember 1 according to the above-described first embodiment only in thestructure of each bracket 620. The other structural features aresubstantially the same as those of the first embodiment. Therefore, theyare given reference numerals that are the same as those of theircorresponding structural features according to the first embodiment, andare not described below.

As shown in FIGS. 10 and 11, each bracket 620 according to the secondembodiment includes a plate-shaped blank 625 and a reinforcing rib 626,which is joined to one surface of the blank 625. Similarly to the blank1020 according to the first embodiment, each blank 625 includes a narrowwidth portion 621, which is positioned at one end side along onedirection (that is, the direction from the lower left to the upper rightin FIG. 10), and a wide width portion 622, which is positioned at theother end side along the one direction and has a width which correspondsto a length that is greater than the width of the narrow width portion621, the length being defined in a direction orthogonal to the onedirection. Each wide width portion 622 has bolt holes 24.

Each reinforcing rib 626 is disposed so as to extend in the onedirection (that is, the direction of arrangement of the narrow widthportion 621 and the wide width portion 622 of the blank 625) at asubstantially central portion of its corresponding blank 625 in thewidth direction. Each reinforcing rib 626 is shorter than itscorresponding blank 625 in the one direction. One end of eachreinforcing rib 626 is aligned with an end of its corresponding blank625 along the one direction at a side where the narrow width portion 621is formed, and the other end of each reinforcing rib 626 along the onedirection is positioned at the wide width portion 622 of itscorresponding blank 625. One end of each reinforcing rib 626 need not bealigned with the end of its corresponding blank 625 along the onedirection where the narrow width portion 621 is formed. It only needs tobe positioned on the narrow width portion 621 of its corresponding blank625.

In the second embodiment, when the blanks 625 and the reinforcing ribs626 are formed of metallic materials, the blanks 625 and the reinforcingribs 626 may be joined to each other by friction stir welding. In thiscase, as shown in FIG. 12, with each reinforcing rib 626 being incontact with one surface (that is, the lower surface in FIG. 12) of itscorresponding blank 625, a cylindrical rotary tool 901 while beingrotated is pushed against the other surface (that is, the upper surfacein FIG. 12) of each blank 625, and a probe 902 at an end of the rotarytool 901 is fitted to each blank 625 and each reinforcing rib 626. Atthis time, frictional heat that is generated at a location between theprobe 902 of the rotary tool 901 and each blank 625, and at a locationbetween the probe 902 of the rotary tool 901 and each reinforcing rib626 causes plastic flow to occur at a portion where the blank 625 andits corresponding reinforcing rib 626 contact each other. Then, thiscontact portion is cooled and solidified, so that the blank 625 and itscorresponding reinforcing member 626 are joined to each other.

Returning to FIG. 10, the brackets 620 are such that the narrow widthportions 621 to which the corresponding reinforcing ribs 626 are joinedat the corresponding blanks 625 are inserted in the corresponding endsof the cylindrical body member 10. In the second embodiment, thedirection of extension of each reinforcing rib 626 inserted in the bodymember 10 is parallel to the direction of extension of the body member10. The direction of extension of each reinforcing rib 626 only needs tobe along the direction of extension of the body member 10, and may beslightly shifted from its position where its direction of extension isexactly parallel to the direction of extension of the body member 10. Asin the first embodiment, compressed tube portions 11 are provided at twoends of the body member 10, and the body member 10 and the brackets 620are clinched by electromagnetic tube compression.

As shown in FIG. 13, which is a sectional view of the connecting member601 at the compressed tube portion 11, the portion of the bracket 620that is inserted in the body member 10 has a T shape in cross sectionthat is orthogonal to the insertion direction (in FIG. 13, the shape isan inverted T shape). The compressed body member 10 is deformed into anuneven form along the shape of the bracket 620 that is disposed in thebody member 10, and is formed into a partly inwardly projecting shape.

As described above, according to the connecting member 601 of the secondembodiment, the brackets 620 are formed by joining the reinforcing ribs626 to the surfaces of the corresponding plate-shaped blanks 625. Inaddition, the portions of the brackets 620 to which the reinforcing ribs626 are joined are inserted into the body member 10 so that thedirection of extension of each reinforcing rib 626 is substantiallyparallel to the direction of extension of the cylindrical body member10. The body member 10 and the portions of the brackets 620 that areinserted in the body member 10 are clinched by electromagnetic tubecompression.

Therefore, since, as in the first embodiment, the body member 10 and thebrackets 620 are clinched by electromagnetic tube compression, it ispossible to manufacture the connecting member 601 with good precision.In addition, since the brackets 620 are formed by joining thereinforcing ribs 626 to the corresponding plate-shaped blanks 625, thebrackets 620 can be formed with various sizes and shapes. Thus, astructure to which the connecting member 601 is applied can be morefreely designed. Further, each reinforcing rib 626 is joined to theportion of its corresponding bracket 620 that is inserted into the bodymember 10, so that this portion of each bracket 620 has high rigidity.Therefore, when the brackets 620 and the body member 10 are clinched byelectromagnetic tube compression, even if induction current is generatedat the surface of each bracket 620, the brackets 620 are hardlydeformed, and only the nonmagnetic body member 10 at the outer side ofthe brackets 620 is compressed. Consequently, it is possible to fastenthe body member 10 and the brackets 620 with sufficient clinching force.This makes it possible to increase the strength of the connecting member601. In addition, the body member 10 that is compressed is not deformedin the same shape as that before compression. Instead, the body member10 is deformed in a shape having an uneven portion in accordance withthe shape of the portions of the brackets 620 to which the reinforcingribs 626 are joined. Therefore, it is possible to increase the strengthbetween the brackets and the body member in the rotation direction (thatis, withstand load in the rotation direction). Further, each reinforcingrib makes it is possible to considerably increase bending load of itscorresponding bracket.

Still further, in the connecting member 601 according to the secondembodiment, by joining the blanks 625 and the reinforcing ribs 626 toeach other by friction stir welding, the effects of thermal distortionon connection members resulting from melt welding can be reduced.Therefore, it is possible to manufacture the brackets 620 with goodprecision.

Modification of the Second Embodiment

Next, a modification of the above-described second embodiment isdescribed with reference to FIGS. 14A, 14B, and 15. A connecting memberaccording to the modification differs from the connecting memberaccording to the second embodiment only in the shapes of brackets 720corresponding to the brackets 620 according to the second embodiment.The other structural features are substantially the same as those of thesecond embodiment. Therefore, they are given reference numerals that arethe same as those of their corresponding structural features accordingto the second embodiment, and are not described below.

As shown in FIG. 14A, a blank 725 of a bracket 720 according to themodification is bent so that a bend line 725 a extending parallel to asurface of the blank 725 and orthogonal to one direction (correspondingto a direction in which a narrow width portion 721 and a wide widthportion 722 of the blank 725 are arranged and a direction of extensionof a reinforcing rib 726) is formed at a boundary between the narrowwidth portion 721 and the wide width portion 722. The reinforcing rib726 that is joined to the blank 725 has a shape that extends along theshape of the bent blank 725. That is, as shown in FIG. 14B, the bracket720 has a shape having an acute angle in side view from a directionorthogonal to the one direction.

Further, the reinforcing rib 726 has a hollow formed by extrusionprocess as mentioned below. More specifically, a hollow portion 727 isformed in a portion of a side surface of the reinforcing rib 726 (in thedirection of extension thereof) that is joined to the narrow widthportion 721 of the blank 725 and in a portion of a side surface of thereinforcing rib 725 (in the direction of extension thereof) that isjoined to the wide width portion 721 of the blank 725. A recessedportion 728 extending in a direction orthogonal to the direction ofextension of the reinforcing rib 726 is formed in a surface of a portionof the reinforcing rib 726 that is joined to the narrow width portion721. By this, when each bracket 720 and a body member 10 are clinched byelectromagnetic tube compression, the body member 10 that is disposed atthe outer side of each bracket 720 and that is compressed enters therecessed portion 728 of the reinforcing rib 726 of each bracket 720disposed in the body member 10. Therefore, it is possible to prevent thebrackets 720 and the body member 10 from being shifted from each otherafter they have been fastened to each other.

Here, a method for manufacturing a reinforcing rib 726 is described.When manufacturing the reinforcing rib 726, first, as shown in FIG. 15,a plate-shaped molding 1726 having a bend line extending in an extrusiondirection is formed by extrusion process. Here, at the same time, themolding 1726 is formed so that two hollow portions 1727 are formed in anextrusion cross section. In addition, at the same time, the molding 1726is formed so that a recessed portion 1728 extending in the extrusiondirection is formed in a surface of the molding 1726. By cutting themolding 1726 in a direction orthogonal to the direction of extrusion, aplurality of reinforcing ribs 726 are continuously manufactured.

In the modification, it is possible to form a bent portion at eachbracket 720. By this, even if there is an interference object betweenconnection members, it is possible to dispose the connecting member awayfrom the interference object. Therefore, a structure can be even morefreely designed. By cutting to a predetermined width the reinforcing rib726 after extrusion by extrusion process, it is possible to continuouslyform a plurality of reinforcing ribs 726 and to easily form bracketshaving uneven portions in the extrusion direction. Further, by forming ahollow in each reinforcing rib 726, it is possible to reduce the weightof the connecting member.

Although preferred embodiments of the present invention are described,the present invention is not limited to the above-described embodimentsand modifications. Therefore, various changes in design may be madewithin the scope of the claims.

Although the body member 10 according to each of the first and secondembodiments and the cylindrical portions 21 of the brackets 20 accordingto the first embodiment are cylindrical, their shapes are not limitedthereto. They may have, for example, the shape of a cylinder whose crosssection is an ellipse or a square.

Although, in the first embodiment, the brackets 20 are mounted tocorresponding end portions of the body member 10, and, in the secondembodiment, the brackets 620 are mounted to corresponding end portionsof the body member 10, at least one of the two ends of the base member10 has a bracket 20 or a bracket 60 mounted thereto.

The materials of the brackets 20 and 620 are not limited to soft steel.The materials thereof may be high-tensile steel that is difficult toweld. The brackets 20 and 620 may be formed of nonmagnetic materials.Therefore, the brackets 20 and 620 may be formed of, for example,high-strength aluminum having low conductivity (2000 series, 7000series) or a highly insulative resin.

Although, in the second embodiment, the blanks 625 and the reinforcingribs 626 of the brackets 620 are joined to each other by friction stirwelding, the method for joining the blanks 625 and the reinforcing ribs626 is not limited thereto. That is, the blanks 625 and the reinforcingribs 626 may be joined by, for example, melt welding (such as laserwelding, electron beam welding, or metal inert gas (MIG) welding); usingbolts; or a combination of these. When the blanks 625 and thereinforcing ribs 626 are formed of resin, such ascarbon-fiber-reinforced plastic (CFRP), the blanks 625 and thereinforcing ribs 626 may be joined with an adhesive.

Although, in the second embodiment, one reinforcing rib 626 is joined toone of the surfaces of its corresponding blank 625, for example, two ormore reinforcing ribs may be joined to one of the surfaces of itscorresponding blank 625. Alternatively, two reinforcing ribs may bejoined, one to each surface of the blank 625.

What is claimed is:
 1. A connecting member of a structure, comprising: acylindrical body member formed of a nonmagnetic, electrically conductivematerial; and a bracket including a cylindrical portion and aplate-shaped portion that are integrally formed, the cylindrical portionbeing provided at one end side of a plate material along one directionand being provided with a slit extending over an entire length of thecylindrical portion in the one direction as a result of forming aportion at the one end side of the plate material along the onedirection into a cylindrical shape extending in the one direction,whereby an induction current in the cylindrical portion of the bracketduring electromagnetic tube compression is reduced by the slit, theplate-shaped portion being provided at the other end side of the platematerial along the one direction, wherein at least one of two innersides at corresponding end portions of the body member has insertedtherein the cylindrical portion of the bracket, the body member isplastically deformed by electromagnetic tube compression and thecylindrical portion and the body member are clinched by theelectromagnetic tube compression.
 2. The connecting member of astructure according to claim 1, wherein the body member is bent.
 3. Theconnecting member of a structure according to claim 1, wherein at leastpart of the body member is flattened.
 4. The connecting member of astructure according to claim 1, wherein the body member is bent, and atleast part of the body member is flattened.